Thrombocytopenia is relatively common in sick newborn infants. In preterm infants it can occur in association with such clinical entities as sepsis, growth retarded infants of mothers with pre-eclampsia and infants who suffered from intrapartum asphyxia. The hypothesis that infants with these clinical conditions may develop neonatal thrombocytopenia from a temporary deficiency of TPO is under investigation here. If this is found to be true, these conditions would be amenable to treatment with recombinant human thrombopoietin, which will soon become available for initial clinical trials. The aim of this study is to examine and quantify thrombopoietin levels in thrombocytopenic newborns. Status: Subject enrollment and data analysis completed.